The present invention relates generally to occupant detection technology to be installed in a vehicle and, more particularly, a technology for detecting information about a rear-seat occupant sitting in a rear seat of a vehicle.
Conventionally, various techniques are known for detecting an object occupying a vehicle seat by using a photographing means such as a camera. For example, disclosed in Japanese Patent Application No. 2006-316138 is a configuration of an occupant detection apparatus in which a camera capable of two-dimensionally photographing an object is arranged in front of a vehicle occupant to detect the position of the vehicle occupant by the camera.
Seat belt apparatuses may be attached to a vehicle rear seat for restraining an occupant. With such apparatuses, for example, there is a demand to increase the seat belt wearing rate by rear-seat occupants. To serve this demand, the vehicle may detect precise information about a rear-seat occupant that may be actually sitting in the vehicle rear seat. Technology for detecting the information regarding a rear-seat occupant may also be effective for a seat belt apparatus for the rear-seat occupant, a drive assist apparatus, etc.
However, it is difficult to precisely detect desired information about a rear-seat occupant when using a camera to two-dimensionally photograph a vehicle occupant, for example as with the detecting apparatus disclosed in Japanese Patent Application No. 2006-316138. When there is a small difference in color between the background and a rear-seat occupant or a small difference in color between the skin and the clothes, a problem arises that makes it difficult to securely detect the rear-seat occupant. Therefore, there is a need to provide a technology that is effective for more precisely detecting information about a rear-seat occupant sitting in a vehicle rear seat.